y=x^2-4
求导y'=2x
设切点为A(m,n)
则切线斜率k=2m
切线方程为y=2mx-5
A代入y=x^2-4得
n=m^2-4 (1)
A代入切线得：
n=2m^2-5(2)
(1)(2)==>
m=1,n=-3 ,或m=-1,n=3
阴影面积
S=2ʃ(0,1)[(x^2-4)-(2x-5)]dx
=2ʃ(0,1)(x^2-2x+1)dx
=2[1/3x^3-x^2+x]|(0,1)
=2(1/3-1+1)
=2/3
y=x^2-4
求导y'=2x
设切点为A(m,n)
则切线斜率k=2m
切线方程为y=2mx-5
A代入y=x^2-4得
n=m^2-4 (1)
A代入切线得：
n=2m^2-5(2)
(1)(2)==>
m=1,n=-3 ,或m=-1,n=3
阴影面积
S=2ʃ(0,1)[(x^2-4)-(2x-5)]dx
=2ʃ(0,1)(x^2-2x+1)dx
=2[1/3x^3-x^2+x]|(0,1)
=2(1/3-1+1)
=2/3